Thunder is a recurring character and the sister of Lightning. Along with Lightning, she first appeared as a background character in early episodes, and starting with Seeing Red, she becomes a regular. She is voiced by Cree Summer.
Thunder is a young lady with dark skin, brown eyes and dark brown hair in a ponytail. She wears a black and yellow jumpsuit with a yellow arrow pointing down the center of her torso, yellow sleeves, and black pants, as well as yellow boots.
Thunder argues with her sister; Lightning over a hairband, thanks to the effects of a red kryptomite.